FR2529883A1 - PROCESS FOR THE PRODUCTION OF VINYL CHLORIDE - Google Patents

Abstract

PROCESS FOR MANUFACTURING VINYL CHLORIDE BY CONDENSATION OF METHYL CHLORIDE OBTAINED FROM METHANE OR METHANOL, FOLLOWED BY OXYCHLORATION OF THE CONDENSATION PRODUCTS THEN BY DEHYDROCHLORATION. THE CONDENSATION OF METHYL CHLORIDE IS PREFERABLY CARRIED OUT IN THE PRESENCE OF A CATALYST CHOSEN FROM THE OXIDES, OXYHALOGENIDES OR SULPHIDES OF THE TRANSITION METALS OF GROUPS IV, V, VI AND VII OF THE PERIODIC TABLE OR ALSO AMONG THE ALUMINOSILICATES.

Description

1 -

  The present invention relates to a manufacturing process

  cation of vinyl chloride from methyl chloride.

  Vinyl chloride, whose production has grown significantly over the last 30 years, is used primarily as a monomer

  basis for the manufacture of chlorinated vinyl resins.

  Originally, vinyl chloride monomer was

  manufactured by adding hydrochloric acid to acetylene.

  This process is now replaced by chlorination or

  oxychlorination of ethylene with thermal dehydrochlorination

  These processes are largely

  Written in the literature as for example in "Industrial Organic Chemistry" K WEISSERMEL and J J ARPE, Verlag Chemie,

Weinheim, New York 1978.

  Current manufacturing processes, based on ethylene, are dependent on petrochemical sources in

  particular of naphtha or cracking products of hydro-

light carbides.

  The process according to the invention makes it possible to manufacture vinyl chloride by condensation of methyl chloride followed by an oxychlorination of the condensation products which provides the dichloroethane intermediately.

  dehydrochlorinated in a known manner to vinyl chloride.

  Methyl chloride is usually obtained from

methane or methanol.

  The process can be schematized in three steps as follows: 1 2 CH Cl condensation product + H Ci 2 Condensing products + HC 1 + + 02 oxychlorination C 1 CH 2 CHC 1 + H 20

2 2 2

  -2 - dehydrochlorination 3 Cl CH CH 2 Cl> CH = CH Cl + H Cil

2 2 2

  The hydrochloric acid of the third step can be recovered and recycled to the oxychlorination of the condensation products or to the chlorination of methanol to methyl chloride: CH 3 H + H Cl CH 3 Cl + H 20

  Another possibility for recovering HCL residues

  may be retained, namely: the oxychlorination of the

  thane: CH 4 + HCl + O 2) CH 3 Cl + H Depending on the nature of the raw material used, the overall reaction can be symbolized by one of the two equations: 2 CH OH + H Cl + O> CH = CH Cl + 3 HO

3 2 2 2

  4 CH 4 + C 12 + 2.5 02> 2 CH 2 = CHC 1 + 5H 20

  The condensation according to the first step is a

  chemical action known in itself, but results from

  particularly satisfactory, due to the decrease in

  secondary products, are obtained when it is carried out

  bifunctional acid-base catalyst at a temperature of

  250 to 4501 C and preferably between 325 and 375 C with a gas hourly space velocity (GHSV) of 50

  at 300 and preferably from 75 to 100 Bifunctional catalysts

  recommended derives from chalconids-oxides, oxy-

  halides or sulphides of the transition metals of groups IV, V, VI and VII of the periodic table and particularly of tantalum, niobium, zirconium, tungsten,

  titanium, chromium They are usually deposited on a

  such as alumina, zirconia, silica and the like. Aluminosilicates can also be used as catalysts, such as the acid form of a mordenite having an Si / Al ratio of from

  The condensation can also be carried out in

  of an inert diluent, such as, for example, an excess of

methane or nitrogen.

  The oxychlorination reaction is usually carried out

  in the presence of copper chloride as a catalyst for

  temperatures between 200 and 300 C and more

  particularly close to 250 C under a pressure of 1 to

10 bars.

  The reaction of deshydrochlorination is purely thermal

  The gaseous dichloroethane is converted into vinyl chloride by passing through a reactor at a temperature of 480 to 530 C under a pressure of 5 to 20 bars. In general, about 50% of the dichloroethane is converted into vinyl chloride,

  the unreacted dichloroethane being recycled.

  Methyl chloride can come from chlorine

methanol or methane.

  An interesting method for obtaining methyl chloride is to react on methanol with the acid

  hydrochloric acid, and more particularly hydrochloric acid,

  by-product of the third step described above The reaction can be carried out in the liquid phase,

  between 180 and 240 ° C., in the presence of a base-stock catalyst

  Zn C 12 at a pressure of 1 to 5 bar.

  The molar ratio HC 1 / CH 3 H is preferably between 1.1 and 1.3. This reaction can also be carried out in the vapor phase at a temperature of between 400 and 45.degree.

  presence of alumina as catalyst.

  Such a process makes it possible to directly manufacture vinyl chloride directly from methanol via the intermediate stage of methyl chloride according to the following diagrams: 2 CH 3 H + 2 H Cl> 2 CH 3 Cl + 2 H 2 CH 3 C 1 condensation then 02 Cl CH 2 CH Cl + H 20 Cl CH 2 CH 2 CH 2 = CH Cl + H Cl A neighboring scheme can be envisaged from methane: CH 4 + C) CH 3 C 1 + HCl 3 CH 4 + 3H Cl + 3/2 02 3 CH 3 Cl + 3H 20 4 CH 3 C 1 condensation then 02 2 Cl CH 2 CH 2 Cl + 2 H 20 2 Cl CH CH 2 Cl> 2 CH = CH Cl + 2H Cl

2 2 2

  Chlorination of methane can be carried out at a time

  between 400 ° and 450 ° C. under a slight pressure.

  Methyl chloride can also be obtained

  by photochemistry These processes for obtaining the chloride of

  thyle are for example, described by: F ASINGER "Paraffins

  Chemistry and Technology "Pergamon Press, New York, 1968 -

  M L POUTSMA "Methods in Free Radical Chemistry", Vol II, E.S. Huyser, Ed, M. Dekker, New York 1969 R WEISSERMEL and H J ARPE "Industrial Organic Chemistry" Verlag Chemie,

1978, pp 46-47.

  Another method consists of ionic chlorination-

  methane carried out at a temperature of between 100 and 500 ° C. and more particularly between 200 and 325 ° C. in the presence of a catalyst chosen from the halides or oxyhalides of the metals of groups IV, V, VI of the periodic table, for example tantalum, niobium, zirconium, tungsten, -5-

  titanium, chromium and others, or among the catalysts

  Group VIII metal compounds, such as platinum or palladium This type of catalyst is preferably deposited

  on a suitable support such as alumina or graphite.

  It is also possible to use Bronstead type catalysts such as perfluorinated sulphonic acids or sulphonic acid resins. This ionic chlorination is illustrated in FIG.

  US Patent Application 298390.

  In general, the molar ratio C 12 / CH 4 is usually between 1 and 5 and more precisely between

1,5 and 3.

  The following examples serve to illustrate the invention

  given compositions being calibrated, even if not reported, to provide a conversion rate

total of 100%.

EXAMPLE 1

  In a respective ratio of 3/1 methane and chlorine pass into a tubular reactor at a temperature

  2350 C on a catalyst composed of 10% by weight of oxyfluorocarbon

  tantalum salt deposited on 90% by weight of alumina GHSV

is around 50.

  The reaction product containing, in addition to the excess methane, 96.5% of methyl chloride and 3.5% of ethyl chloride as well as the corresponding hydrochloric acid formed is, without separation, passed through a second reactor on a catalyst composed of 20% of supported tungsten oxide

  with 80% alumina GHSV is about 80, the mixture is

  Zeux passing on the catalyst at a temperature of 3650 C. The product of the condensation step, is extracted methane as well as the unreacted methyl chloride, which is recycled The fraction containing the condensation product including l anhydrous hydrochloric acid is reacted with oxygen in the presence of Cu C 12 as a catalyst in 2 to 3

  atmospheres at a temperature of 220-2,400 C 1,2-dichloro-

  ethane (EDC) obtained with a yield of 95% and a selectivity of 98% is thermally dehydrochlorinated at 5000 C.

  Vinyl chloride is obtained with 98% of

  dichloroethane-based acidity hydrochloric acid

  formed by byproduct is recycled via oxychlorination.

EXAMPLE 2

  320-370 ° C is reacted in a stoichiometric amount.

  Methyl alcohol and hydrochloric acid are

  of alumina as a catalyst The reaction product con-

  methyl chloride, without separation, is directly sent to a condensation reactor, the conditions of condensation, oxychlorination and dehydrochlorination remaining

  identical to those of Example 1.

EXAMPLE 3

  The procedure is carried out under the conditions of Example 1, the tantalum oxyfluoride catalyst being replaced by 0.5% of palladium deposited on 99.5% of alumina and the

  tungsten oxide catalyst of the condensation step

  replaced by the acid form of mordenite Vinyl chloride is obtained with 99% selectivity based on

on the dichloroethane.

Z 529883

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Claims (4)

  1 Process for producing vinyl chloride by condensation   methyl chloride obtained from methane or   methanol, followed by oxychlorination of   densification and dehydrochlorination. 2 Process according to Claim 1, characterized in that the condensation of the methyl chloride is carried out in the presence of a catalyst chosen from the oxides, oxyhalides or sulphides of the transition metals of groups IV, V, VI and   VII of the periodic table, or among the alumino- silicates.   3 Process according to one of claimsi to 2 characterized   in that the hydrochloric acid formed with dehydrochlorination   is recycled to the oxychlorination of condensation products.   4 Process according to one of Claims 1 to 2, characterized   in that the hydrochloric acid formed with dehydrochlorination   is recycled to the chlorination of methanol to methyl chloride.   Process according to one of Claims 1 to 2, characterized   in that the hydrochloric acid formed with dehydrochlorination   is recycled to the oxychlorination of methane to methyl chloride.